The expected value in this case means .

In two coin flips, the number of heads can vary from trial to trial. Each flip has an expected 1/2 head, so the expected number in two flips is 1/2 + 1/2 = 1. This means that over many trials of flipping a coin twice, the average number of heads per trial will approach 1; it does not mean every pair of flips has exactly one head.

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